A method is known of detecting the shape of traveling rolled materials (mainly rolled strip) widthwise thereof by detecting the pressure of the rolled material from portion to portion widthwise thereof with a rotating roll supporting the rolled material over the width thereof and determining the tension and therefore the elongation of the widthwise portions from the pressure.
Such shape detecting rolls are disclosed in Unexamined Japanese Patent Publication SHO 56-82424, etc. An example of such roll will be described with reference to FIGS. 1 to 3.
The illustrated roll comprises a plurality of disks 2 held between a pair of stationary plates 3 on opposite sides and each having a pressure sensor 1 incorporated therein close to its periphery. The disks 1 are arranged axially of the roll concentrically with one another and joined together by tie rods 4. An end member 6 having a projecting roll shaft 5 is fixed to each end of the disk assembly concentrically therewith. The roll shaft 5 is rotatably supported by a bearing.
Each disk 2 has an annular portion 8 positioned inwardly of its peripheral portion and provided on opposite sides thereof with faces 9 for contact with the respective disks adjacent thereto. The pressure sensor 1 is accommodated between the disk peripheral portion 10 and the periphery of the annular portion 8. To assure the pressure sensor 1 of accurate detection, a clearance 11 of about 0.1 mm is provided between the peripheral portions 10 of the adjacent disks for preventing the interference between the peripheral portions 10. A seal groove 12 is formed in each side surface of the peripheral portion 10, and a seal ring 13 is fitted in the seal groove 12 for preventing a coolant or the like from penetrating into the sensor accommodating chamber 14 through the clearance 11. Indicated at 15 in FIG. 3 are holes for reducing GD.sup.2.
Conventionally, the disks 2 are made of SCM material. The disks 2 are plated to obviate the likelihood that the side surfaces of the disk peripheral portions 10 will be corroded to close the clearance 11 if the roll is installed in a line wherein a rolling oil (soluble oil) containing a large amount of water is used or in a seaside area where the roll is exposed to the air containing salt. Thus, the side surfaces of the peripheral portions 10 defining each clearance 11 are coated with a corrosion-resistant plating film.
With the rolling conditions becoming severer in recent years, the pressure detecting roll has been placed into frequent use. To meet the need to give improved abrasion resistance to the roll, steel materials containing large quantities of special components, such as V and Nb, are used for making the disks.
However, if the disk is made of the steel material which permits presence of tough oxides or compounds of special elements, the disk surface can not be fully activated merely by acid pickling or degreasing which is usually conducted as a pretreatment before plating, with the result that the plating is very poor in adhesion and fails to serve for a long period of time.
An object of the present invention, which has been accomplished in view of the above problem, is to provide a shape detecting roll comprising disks which are coated with a corrosion-resistant plating over the side surfaces of the peripheral portions thereof forming a clearance between the adjacent disks, the plating being resistant to peeling regardless of the material used for the disks so as to give high durability to the roll.